Connectors don't connect to the edge of clones

Migrated from: https://bugs.launchpad.net/inkscape/+bug/474881

Steps to reproduce:

open Inkscape
create a rectangle
create a clone (Alt+D while rectangle is selected)
move the clone apart from the rectangle
go to the connector tool (Ctrl+F2)
link the clone to rectangle

What happened?

Connector connects to center of bounding box (probably) instead of the edge of the clone.

File taken from launchpad (suv):

What should have happened?

Clones, bitmaps, symbols, text (maybe) should be handled like shapes if possible (well, bitmaps just need to be treated like rectangles). This issue focuses on clones.

tremby mentioned that grouping the clones doesn't fix the problem.

Inkscape Version and Operating System:

1.0alpha2 (cac6fc55, 2019-07-31), Linux Mint 19.1
Inkscape 0.48.0 r9654 Ubuntu 10.04
Inkscape 0.46+devel r22552, on OS X 10.5.8
Inkscape 0.48.1, OS not mentioned, probably OS X

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